1. Field of the Invention
The invention relates to hands-free access and/or starting systems for motor vehicles.
2. Description of Related Art
Such systems comprise a control unit installed in the vehicle and a portable identifier suitable for communicating remotely and cordlessly with the control unit in order to be authenticated by the control unit. The portable identifier is not especially intended to be rendered integral with the vehicle when the latter is running as is the case with a mechanical contact key. In the case of the lending of vehicles equipped with such hands-free access and/or starting systems, in particular for vehicle rental firms and company vehicle fleets, the fact that a user of a vehicle hands back the identifier associated with this vehicle is not sufficient to prove that this vehicle""s engine has been stopped. Indeed, the vehicle may continue to run, engine ticking over, although the identifier has been returned to the owner of the vehicle. In this case, the owner of the vehicle is unable to ascertain whether the theft of the vehicle was committed by the last user of the vehicle or by a third party.
The object of the invention is therefore to make the operation of hands-free access and/or starting systems for motor vehicles secure so as to limit the possibilities of fraud in particular in the situations indicated above.
Accordingly, the subject of the invention is a method of making secure a hands-free access and/or starting system for a motor vehicle, the hands-free system comprising a control unit placed in the vehicle and a portable identifier suitable for communicating remotely and cordlessly with the control unit in order to be authenticated, the method being characterized in that it consists in recording a first data item in the identifier by communicating with the control unit in response to detecting starting of the vehicle engine, and in recording a second data item to replace the first data item in the identifier by communicating with the control unit in response to detecting normal stopping of the vehicle engine.
Consequently, with this method, when the identifier is returned by the user, it is possible to ascertain whether the vehicle has been left with the engine ticking over or with the engine stopped by this person depending on whether the identifier contains the first or the second data item in memory. The reading of this data item may be done directly on a display screen provided on the identifier or by way of a reader terminal to which the identifier will be connected up.
According to a particular embodiment of the method according to the invention, said first and second data items are recorded in the identifier and in the vehicle so as to prove a break-in in the case of the theft of the vehicle. Indeed, when this vehicle is recovered, if the latter contains the first data item, this signifies that it was left in an unauthorized manner by the last person who returned the identifier. Conversely, if the latter contains the second data item, this signifies that this last person left the vehicle normally.